Evaluation of alveolar surfactant aggregatesin vitroandin vivo

Abstract

In acute lung injury, a decrease in surface-active large aggregates and an increase in the less surface-active small surfactant aggregates are observed. The objective of the current study was to determine if the increase in small aggregates interfered with the function of large aggregates, thereby independently contributing to lung dysfunction.Isolated large aggregates, small aggregates, and large aggregatezsmall aggregate combinations were analysed for in vitro surface activity utilizing a pulsating bubble surfactometer. Subsequently, large aggregates, small aggregates, and large aggregatez small aggregate combinations were administered to surfactant-deficient, adult SpragueDawley rats. Physiological parameters were measured during 1 h of ventilation. After sacrifice, the whole lung lavage was analysed for protein concentration, and surface activity of the recovered large aggregates.The minimum surface tension of the large aggregatezsmall aggregate preparations (10 mN?m -1 ) was significantly higher than large aggregates alone (1 mN?m -1 ), but lower than small aggregates alone (21 mN?m -1 ) after 100 pulsations. In vivo, rats receiving large aggregateszsmall aggregates showed immediate increases in oxygenation, similar to animals given large aggregates, whereas animals given small aggregates and control animals maintained low oxygenation values.In conclusion, small aggregates interfered with large aggregates function in vitro, but this was not observed in vivo in this experimental model.

Chitosan Enhances the In Vitro Surface Activity of Dilute Lung Surfactant Preparations and Resists Albumin-Induced Inactivation

“…It has been demonstrated that in a pure phospholipid vesicle system, PEG at certain molecular weights and concentrations can induce a depletion-attraction force that promotes the formation of large phospholipid aggregates (30). Large aggregates are known to be more surface active than their smaller counterpart both in vitro (31) and in vivo (32). Theoretical study has established that the depletion attraction force is proportional to the aggregate radius (28).…”

Functional importance of the NH2-terminal insertion sequence of lung surfactant protein B

“…The animal experiments were performed with the approval of the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center Institutional Animal Care and Use Committee. Anesthesia, surgery, lavage, ventilation, and monitoring used in this study are the same as previously described (8,23). Briefly, adult male Sprague-Dawley rats weighing 200 -225 g were anesthetized with 35 mg/kg sodium pentobarbital and 80 mg/kg ketamine by intraperitoneal injection, intubated, and ventilated with a rodent ventilator (Harvard Apparatus, South Natick, MA) with 100% oxygen, a tidal volume of 7.5 ml/kg, a positive end-expiratory pressure (PEEP) of 3 cmH 2O, and a rate of 60/min.…”

Dipalmitoylphosphatidylcholine is not the major surfactant phospholipid species in all mammals

“…The large aggregate subfraction contains dense structures and apoproteins that are responsible for the surfaceactivity of surfactant and hence maintain alveolar stability. Lighter, vesicular forms of surfactant that are undergoing recycling or clearance from the lung and are less surface-active, are present in the small aggregate fraction (8). The subfractions of dunnart surfactant were resuspended in 2 ml of deionized water for analysis of surfactant proteins.…”